PNNL

Abstract

The planetary boundary layer height (PBLHT) is an important parameter influencing a variety of atmospheric processes. Ceilometer measurements of aerosol backscatter profiles have been widely used to provide continuous PBLHT estimations. To investigate the robustness of ceilometer-estimated PBLHT under different atmospheric conditions, we compared ceilometer- and radiosonde-estimated PBLHTs using multiple years of U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) ceilometer and balloon-borne sounding data at three ARM fixed-location atmospheric observatories and from three ARM mobile observatories deployed around the world for various field campaigns. Statistical comparisons of ceilometer-estimated PBLHTs from the Vaisala CL31 ceilometer data with radiosonde-estimated PBLHTs from the ARM PBLHT-SONDE Value-added Product (VAP) are performed under different atmospheric conditions including stable and unstable boundary layer, low-level cloud-free, and cloudy conditions at these ARM observatories. Under unstable boundary layer conditions, low- and mid-latitude land observatories have good comparisons between ceilometer- and radiosonde-estimated PBLHTs. It is still challenging to obtain reliable PBLHT estimations over ocean surfaces even using radiosonde data. Under stable boundary layer conditions, ceilometer- and radiosonde-estimated PBLHTs have weak correlations and the bulk Richardson number method is more suitable for estimating PBLHTs with radiosonde data. We recommend that advanced PBLHT estimation methods such as that use the machine learning technique have the potential to greatly improve PBLHT estimations from both ceilometer and radiosonde data.